Method of forming non-frangible metallurgical briquettes



United States Patent 3,264,090 METHOD OF FORMING NON-FRANGIBLE METALLURGICAL BRIQUETTES Edwin H. Swartz, P.O. Box 1033, Sanford, N.C. No Drawing. Filed Apr. 26, 1965, Ser. No. 451,035 11 Claims. (Cl. 753) This application is a continuation-impart of my prior co-pending application Serial No. 268,686, filed March 28, 1963, now Patent No. 3,180,722.

This invention relates to a new and useful method for recovering metallic waste'products and more particularly to the formation of metallurgical briquettes from such waste products.

The present invention embodies certain improvements over the invention as described and claimed in my said prior co-pending application. Therefore, it is the primary object of the present invention to provide a method of forming non-frangible briquettes from waste products such as cast iron products in an economically feasible manner.

In preparing the briquettes in accordance with the improved method of the present invention, the metallic particles such as cast iron are mixed with a relatively small amount of binder material such as Portland cement in an inactive state after which the mixture is compressed into a cohesive mass or briquette. Thereafter, the briquette is submerged within an activating liquid as described in the aforementioned prior co-pending application. However, While the binder is being activated by the liquid, it is also brought into contact with an accelerator, or hardener so as to regulate the rate at which the binder is activated as well as to reduce the curing time and improve the impact resistant quality of the outer protective crust finally formed. In view of the substantial reduction in curing time and improvement in the impact resistant property of the briquettes, the benefits derived lfI'OITl the improved method are substantial. Further, the additional cost attributable to the improvement over the method as previously described and claimed in the prior copending application aforementioned, are minimal and well worth the qualitative improvement in the briquettes and the inventory advantage obtained by the reduction in curing time. The use of the activating accelerator, within the method of the present invention may be effected by forming a solution with the binder activating liquid so that the binder material will be brought in contact therewith when the briquette is submerged within the liquid. Alternatively, the accelerator could be added or mixed with the binder and the metallic particles prior to briquetting thereof.

It is therefore an additional object of the present invention to provide an improved method of forming metallurgical briquettes that are non-frangible by introducing an accelerator or hardener .to regulate the rate at which the binder is activated within an outer layer portion of the briquette as well as to substantially reduce the curing time.

A still further object of the present invention is in accordance with the foregoing object, is to provide an improved method of forming non-frangible briquettes by utilizing a binder activating solution containing an accelerator such as a chloride salt which will substantially reduce the process time as well as to improve the impact resistant property of the product.

These together with other objects and advantages which will become subsequently apparent reside in the details of the method steps and product formed therefrom as more fully hereinafter described and claimed.

The method of the present invention involves the formation of a cohesive body or metallurgical briquette composed essentially of metallic particles such as cast iron. These particles are collected as shavings or borings so that they may be remelted in a cupola. However, in order to handle, transport and charge the cupola with these metallic particles, they are compressed into coherent masses or bodies formed by a conventional briquetting press. When dealing with cast iron particles, there is a tendency for the briquette body to fall apart or crumble inasmuch as cast iron itself has poor impact resistant properties. Prior to briquetting of the cast iron particles, a small quantity of slag forming binder materials such as Portland cement is mixed with the particles. Accordingly, after the briquettes are formed, they will be composed essentially of a mixture of cast iron particles and a relatively small quantity of cement distributed throughout the briquette body.

After the briquette is removed from the briquetting press, it is immersed in a binder activating liquid for activation of the binder limited to an outer layer portion of the briquette as described in the aforementioned prior copending application. However, in accordance with the present invention, the activating liquid is formed by a solution of salt in water. The salt of the brine solution acts as an accelerator or hardener in that it reduces the time necessary to maintain the briquette submerged within the binder activating liquid in order to activate a sufiicient amount of the binder necessary to form the protective crust as well as to susbtantially reduce curing time. Utilizing approximately five percent by weight of sodium chloride as the accelerating salt in the brine solution, satisfactory results have been obtained when maintaining the briquette submerged for a period of 36 hours under ambient atmospheric conditions as compared to the approximately two days found necessary in connection with the method as described in the aforementioned prior copending application.

After the briquette has been submerged within the binder activating liquid or brine solution, it is removed for air drying under ambient atmospheric conditions in order to cure the activated cement. Because of the use of the accelerator as aforementioned, satisfactory results have been obtained with a curing time of approximately 72 hours. Further, the product so formed exhibits better impact resistant properties than obtained with the method as described in the prior copending application aforementioned. The impact resistant quality of the briquettes is apparently obtained because of the formation of an outer crust from the binder activated Within an outer portion of the briquette before the inner portion is completely activated. The rather slow activation of the binder is apparently due to the fact that when the cast iron particles are compressed within the briquetting press, the cast iron material is restored to its original bulk density. No critical timing is therefore required for the period during which the briquette is submerged. However, by substantially reducing the lower limit of the submergence period by use of an accelerator, inventory control over the briquettes submerged in the liquid may be substantially facilitated.

It will be apparent from the foregoing, that the amount of accelerator material may be varied in order to regulate the rate at which the binder is activated and the time necessary for curing thereof in accordance with different requirements. Also, although sodium chloride has been found satisfactory as the accelerator or hardener, the other chloride salts will also be suitable. It will also be apparent, that the accelerator could be introduced by mixing it with the Portland cement and the cast iron particles prior to briquetting. Either alternative for introducing the accelerator will add little to the cost of the particle recovery procedure yet will result in substantial benefits so as to render the improvement of considerable value.

The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact proportions, materials and procedures described, and accordingly all suitable modifications and equivalents may be resorted to, falling Within the scope of the invention as claimed.

What is claimed as new is as follows:

1. A method for preparing a briquette from particulate material comprising the steps of: mixing said particulate material with a binder in an inactive state; compressing the mixture of particulate material and inactive binder into a coherent mass; submerging said coherent mass within a liquid for activating said binder; introducing an accelerating material for contact with the liquid and the binder when submerged therein to regulate the rate at which the binder is activated; withdrawing said coherent mass from the liquid as soon as the binder within an outer portion of the coherent mass is activated; and curing the binder activated to form a protective crust rendering the mass non-frangible.

2. The method of claim 1 wherein said accelerating material is a chloride salt.

3. The method of claim 2 wherein said accelerating material is introduced by forming a solution with said liquid.

4. The method of claim 1 wherein said accelerating material is introduced by forming a solution with said liquid.

5. The method of claim 1 wherein said accelerating material is introduced by mixing with the particulate material and the binder.

6. The method of claim 1 wherein said coherent mass is submerged within the liquid and cured by air drying under ambient atmospheric conditions.

7. The method of claim 6 wherein said coherent mass is submerged in the liquid for approximately 36 hours and then air dried for approximately 72 hours.

8. A non-frangible metallurgical briquette having an internal portion and an external protective layer, said portion and layer both consisting of substantially the same compressed mixture of cast iron particles, a binder and an activating accelerator, the binder within said internal portion being in a relatively inactive state while the binder within said external layer forms an impact resistant surface with the cast iron particles.

9. The article defined in claim 8, wherein the accelerator is a chloride salt.

10. A method of recovering cast iron particles for remelting comprising the steps of: mixing said cast iron particles with Portland cement in a relatively inactive state; compressing the mixture of Portland cement and cast iron particles into a cohesive briquette; submerging said briquette within an aqueous brine solution for activating the cement within an outer layer portion of the briquette; withdrawing the briquette from the brine solution before the cement within a substantial inner portion of the briquette is completely activated; and drying the briquette for curing the activated cement to form an outer crust rendering the briquet non-frangible 11. The method of claim 10 wherein said briquette is submerged within the brine solution and air dried under ambient atmospheric conditions.

No references cited.

BENJAMIN HENKIN, Primary Examiner. 

1. A METHOD FOR PREPARING A BRIQUETTE FROM PARTICULATE MATERIAL COMPRISING THE STEPS OF: MIXING SAID PARTICULATE MATERIAL WITH A BINDER IN AN INACTIVE STATE; COMPRESSING THE MIXTURE OF PARTICULATE MATERIAL AND INACTIVE BINDER INTO A COHERENT MASS; SUBMERGING SAID COHERENT MASS WITHIN A LIQUID FOR ACTIVATING SAID BINDER; INTRODUCING AN ACCELERATING MATERIAL FOR CONTACT WITH THE LIQUID AND THE BINDER WHEN SUBMERGED THEREIN TO REGULTE THE RATE AT WHICH THE BINDER IS ACTIVATED; WITHDRAWING SAID COHERENT MASS FROM THE LIQUID AS SOON AS THE BINDER WITHIN AN OUTER PORTION OF THE COHERENT MASS IS ACTIVATED; AND CURING THE BINDER ACTIVATED TO FORM A PROTECTIVE CRUST RENDERING THE MASS NON-FRANGIBLE. 